Never seen this before. Replaced the black cartridge a few hours ago and finished that job. Shut the machine off. Just turned it on and it showed that all the cartridges were empty. Tried to shut off to restart...it eventually did shut off but took way longer than normal to shut down. That didn't fix it so I pulled all the cartridges out and put them back in. That seemed to do the trick or it was just a coincidence on the next start up that it worked. Anyone seen this before? On a related note I do have problems quite frequently with the machine recognizing when I put in a new cartridge. Sometimes I have to pull it out and back in several time before I finally accepts it as a new one. Guessing these may be related?